Wolfgang W. Bein Mordecai J. Golin Lawrence L. Larmore Yan Zhang The Knuth-Yao quadrangle-inequality speedup is a consequence of total-monotonicity. 31-40 2006 conf/soda/2006 SODA http://doi.acm.org/10.1145/1109557.1109562 db/conf/soda/soda2006.html#BeinGLZ06